SEOUL - South Korea and the United States have begun an annual, routine military exercise involving thousands of personnel. North Korea’s young, untested leader has called for his country’s troops to retaliate, should their territory be infringed during the war games.

The command post drill, named “Key Resolve”, features thousands of personnel. U.S. and South Korean military officials are stressing it has no connection to current events on the Korean peninsula.

A spokesman at South Korea’s Defense Ministry, Kim Min-suk, calls the exercise routine, explaining it will be similar in scope and size to last year’s drill.

Kim says the drill will go on as planned, despite the threats related to it made by North Korea.

Pyongyang is characterizing the exercise as a rehearsal for an invasion by “war mongers” carrying nuclear war equipment. It has also expressed outrage about the timing, calling Key Resolve an infringement of its sovereignty and dignity of the DPRK coming at a time North Koreans are in a period of mourning for their recently deceased leader.

Official state media in Pyongyang says supreme commander Kim Jong Un has personally ordered a frontier unit to be prepared for battle.

The announcer, on the Sunday evening main television newscast, saying General Kim has told front-line soldiers if the “enemy intrudes even 0.0001 millimeters into the waters” of North Korea they should make a powerful retaliatory strike.

There are no indications pointing to unusual military movements in the North.

Since the death in December of Kim Jong Il, North Korea’s rhetoric has grown more bellicose as it transfers top authority and titles to the late leader’s third son.

Analysts note similar threats from Pyongyang have been common over the years but are rarely acted out. However, North Korea, in November, 2010, shelled an inhabited island in the Yellow Sea during a South Korean artillery drill, killing four people. That came eight months after the sinking of a South Korean naval vessel, which an international investigation concluded was caused by a North Korean torpedo.

Another U.S.-South Korean exercise, named “Foal Eagle,” is to begin Thursday and will continue through the end of April. It is to involve more than 11,000 U.S. military personnel plus South Korean army divisions and smaller units.